146 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XXIX.) 
that case was 144 square inches, and the effect per revolution 2°'61. With the long 
rectangles the area is 128 square inches, and the mean of the two results is 2°’312 per 
revolution. Now 144 square inches is to 128 square inches as 2°'61 is to 2°'32 ; a 
result so near to 2°’312 that it may be here considered as the same; proving that 
the electric current induced is directly as the lines of magnetic force intersected by 
the moving wire*. 
3200. It may also be perceived that no difference is produced when the lines of 
force are chiefly disposed in the direction of the motion of the wire, or else, chiefly 
in the direction of the length of the wire ; i. e. no alterations are occasioned by varia- 
tions in the velocity of the motion, or of the length of the wire, provided the amount 
of lines of magnetic force intersected remains the same. 
3201. Having a square on the frame 12 inches in the side but consisting of copper 
wire O’ I of an inch in thickness, I obtained the average result of many observations 
for one, two, three, four and five revolutions of the wire. 
One revolution gave 7 equal to 7 per revolution. 
Two revolutions gave 13*875 equal to 6’937 per revolution. 
Three revolutions gave 2 TO 75 equal to 7'025 per revolution. 
Four revolutions gave 28’637 equal to 7'159 per revolution. 
Five revolutions gave 37*637 equal to 7*527 per revolution. 
These results are exceedingly close upon each other, especially for the first 30°, and 
confirm several of the conclusions before drawn (3189. 3199.) as to the indications of 
the instrument, the amount of the curves, &c.t 
* Oblong rectangles of 128 square inches area give a mean of 20°'81 (3198.). The rectangle of 144 square 
inches gave a mean of 23°'62 (3197.). 
20'81 . o o < 
sin — =sin 10-405 = sm 10 24-3=-1806049 
2 
. 23*62 
= sinll*81 =sinll 48*6=*2047069 
128_8 
144 9 
•1806049 
•1806049x9=1*6254441 
•2047069 X 8=1-6376552 
Or thus : ® 
•2047069 
= •0225756 
•0227452 
• 7 .0 
sm-= sm 3*30 
Differences. 
= •0610485 
13-875 . „ o ! 
= sm 6-9375= sin 6 56-25 = -1207866 
sm 
2 
21-075 
2 
. 28-637 
sm 
sm 
2 
37-637 
= sin 10-5375= sin 10 32-25 = ‘1828790 
= sin 14-3185= sin 14 19-11 = -2473119 
= sin 18-8185= sin 18 49-ll=-3225714 
•0610485 
•0597381 
•1207866 
5 =-0603933 
•0620924 
•1828790_.pgQg^gg 
o 
•0644329 
’2473119_.Qgjg279 
4 
•0752595 
5 
